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      Quadzilla Tunes   06/12/2017

      QUADZILLA TUNE REPOSITORY - There is now a Quadzilla tune download area. When you submit a tune file to the download area it will automatically create a forum topic that allows discussion of your tune. So export your tune and upload it to the site. Then we all can help out in building better tunes. Check it out gang...
    • Mopar1973Man

      911 Support Group   06/22/2017

      Hey Gang, I've got the 911 support group database back up and running once again. It's listed in the 911 support category. It will allow members to list their contact information and location so other have a listed of members to call upon in the time of need. So if you wish to support other member please stop by and add your listing into the database. https://mopar1973man.com/cummins/911-support.html/contacts/

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ISX

Speed/RPM calc..

3 posts in this topic

Spent a while making this thought you guys could have some fun with it too. You have to have microsoft excel for this file to work. Should work with any version.Don't mess with anything but the highlighted blue things or you might erase my formulas. If you do manage to delete it all and make it go nuts, just delete it and redownload the one here..

Speed-RPM 2.xls

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good work....really easy to use...thanksbut what is "Tire Thickness percentage (Required)" and how does that play a role?

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good work....really easy to use...thanks but what is "Tire Thickness percentage (Required)" and how does that play a role?

The middle of the tire formula (245/75/16) is a percentage... The 245 is the width of the tire in mm's. The 75 tells you how much of the width of the tire the sidewall height contains. As in, from the edge of the wheel to the outer part of the tire, is 75% of 245. Obviously this is America and we need English units so you convert 183.75 (75% of 245) into inches by multiplying that by 0.0393700787, now you have about 7.23", so if you measured the sidewall on that tire (the stock size) it would measure almost 7 1/4". So to get tire height you multiply 7.23 by 2 (since there are 2 sidewalls in tire height) and then add the wheel size of 16". Now you have a 30.5" tire.. Let me know if you don't understand that. Alright I updated the file it to make that part a little clearer.

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